In application Ser. No. 881,108, filed Feb. 24, 1978, now abandoned, and Ser. No. 45,047, filed June 4, 1979, now U.S. Pat. No. 4,273,685, there is disclosed as asphalt composition which has been chemically modified with the rubbery polymer to increase fire retardancy and chemical reactivity of the asphalt. The modification of the asphalt with a rubbery polymer also has been found to promote compatability between the asphalt and reinforcements used with the asphalt, notably glass fibers, glass flake and other organic and inorganic fillers and reinforcements.
The chemically-modified asphalts disclosed in the foregoing copending applications are prepared by reaction of a bitumen, and preferably asphalt, with a vinyl aromatic monomer such as styrene and a rubbery polymer. It has been postulated that the vinyl aromatic monomer employed as a coreactant is polymerizable with ethylenic unsaturation contained in the bitumen and thus serves to couple, by means of chemical bonds, the asphalt molecules with the rubber polymer. The resulting chemically-modified asphalt can thus be cross linked with the use of a suitable cross-linking agent well known to those skilled in the art. In addition, the rubbery polymer which has been chemically bonded to the asphalt can serve as a source of reaction sites to establish a chemical bond between the chemically-modified asphalt and reinforcing fillers such as glass fibers, siliceous aggregate, glass flake and combinations thereof which may be blended with the chemically-modified asphalt in reinforced asphalt systems.